The coalition, known as the Permanent Strategic Framework (CSP), pledged its allegiance to Mali's transitional authorities. It downplayed reports of tensions between its members and the national army.

The CSP said it was also declaring war against the al-Qaeda-linked Support Group for Islam and Muslims (JNIM) and a section of Coordination of Movements of the Azawad (CMA), which recently formed an alliance against IS.

"We will go wherever the Islamic State commits massacres to secure civilians and their property and to secure the movements of displaced persons," a CSP representative is quoted as saying.

The coalition said it had taken this decision after the army and Russian mercenaries from the Wagner Group had failed to tackle IS militants despite their presence in Ménakain north-eastern Mali.

About 380 vehicles and nearly 2,500 men have been mobilised with the aim of defending the region against jihadists who have been accused of carrying out deadly attacks against civilian targets, according to the report.